| English | Absolute zero |
|---|---|
| Bahasa Melayu | Sifar mutlak |
| 中文 | 绝对零度 |
Definition
The lowest possible temperature, 0 K or about −273.15 °C, at which the particles of a substance have minimum kinetic energy.
In exam terms
Absolute zero is the lowest possible temperature, equal to 0 K or about −273.15 °C. At this temperature the particles of a substance have their minimum possible kinetic energy, and a gas would (in theory) exert zero pressure and occupy zero volume. It is the zero of the Kelvin (absolute) temperature scale.
Absolute zero is found by extrapolating a pressure–temperature or volume–temperature graph for a gas back to the point where the pressure or volume would become zero; that point falls at about −273 °C. Example of correct use: cooling a gas can never bring it below absolute zero, because its particles cannot have less than zero kinetic energy.
Do not confuse it with…
Do not confuse absolute zero with the absolute temperature scale. Absolute zero is a single fixed temperature (0 K), while the absolute temperature scale is the whole Kelvin scale that begins at that point.
Also do not confuse it with 0 °C, which is the freezing point of water (273 K), not the coldest possible temperature.
In Paper 2 this is usually asked as state the value of absolute zero or explain how absolute zero can be found from a graph. The expected answer links it to minimum particle kinetic energy and to the extrapolation of a p–T or V–T graph to zero.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)